GTA: Sentry Knight

Life as we know it is peaceful and everything is in order, but the forces of darkness doesn't like this. They launch an attack on the human world. Fortunately one brave knight stand against them. Using his crossbow, he would repel the attack with all of his might.
The idea here is to kill enemies before it can even get closer to the tower. You need to make sure that no enemies get near you or you would get toast. You earn money after every level. You can use the money to buy upgrades for your weapon. You can buy magic spells with skill points.